This school is pretty corrupt... even the allies are quite immoral. What if they didn't find the evidence (plot armor)? What kind of punishment would he have? Framing him, after paying him a million to attend, and then going without punishing the real culprit because they are your offspring seems a bit suspect... The MC wears a thick plot armor but doesn't have the intellect and cunning to really deal with this kind of plot.
Honestly, I don't think NDA's protect unlawful conduct from being shared with authorities. Then again, this is what China? idk..